In the electrical grid, electricity is distributed to loads, such as homes in a residential neighborhood, commercial and industrial facilities, and the like, at medium voltages (MV) before the MV is stepped down to low voltage (LV) in close proximity to the load. A distribution transformer is typically used to provide step down of voltage from MV to LV. The LV output of the transformer is connected to the one or more loads. An electrical connection between the transformer and the one or more loads is established by conductors, which may be underground or overhead depending on the type of distribution system. A typical distribution transformer may be connected to a single load up to 12 or more loads depending on the size of transformer. If a split phase distribution transformer is used, the number of load connections may be thirty-six or more, e.g., twelve loads or more, each having three connections per load.
To address various challenges related to the electrical grid, different types of electrical devices may be inserted between the distribution transformer and the one or more loads. For example, in-line electrical devices, such as in-line power regulators or in-line impedances use an electrical connection between the transformer and the one or more loads which is routed through the electrical device. In this example, the LV output of transformer is connected to the source side of the electrical device and load side of the electrical device is then connected to the one or more loads. If a generator or other energy sources, such as batteries is connected to the distribution transformer, the LV output of distribution transformer is disconnected from the one or more loads and the one or more loads is connected directly to the electrical device. A switch can be used to alternate the connection between the transformer and electrical device.
To connect the electrical device to the distribution transformer and the one or more loads, reconstructing wires or conductors connecting to the one or more loads can often be cost prohibitive, especially for an underground distribution system. Additionally, the cost further increases with higher number of loads. One cost effective, and less disruptive, technique to insert the electrical device between the one or more loads and the distribution transformer is to use the existing conductors between the distribution transformer and the one or more loads. This may be achieved by breaking the electrical connection between the distribution transformer and the one or more loads and providing electrical connections from the electrical device to the distribution transformer and to the one or more loads in close proximity to the transformer.
In this example, the load connections at the LV outputs of transformer are disconnected and the load connections are coupled to the electrical device. This requires splicing of one or more conductors, depending on the number of loads to the conductor, and establishing the electrical connection to the electrical device. Different types of conventional splicing devices are known to form an electrical bond between multiple conductors while providing protection against water and other environmental factors. In the example of underground distribution system, a commonly used splicing device is a submersible secondary distribution connector which includes a rubber coated boot and a set screw terminal block with multiple ports to accept multiple conductors and electrically bond them together.
There are several shortcomings associated the method of connecting the electrical device to one or more loads discussed above. In order to utilize the conventional splicing devices, the connections between load conductors and distribution transformer need to be removed. The load conductors are then cut back to proper length so that conductors can be terminated at the new splicing device which may result in long installation times. Moreover, this operation typically requires the distribution transformer to be de-energized, which results in a disruption of service to the one or more loads during installation time. In addition to installation time, new connectors are also needed which further increases costs. The new terminal to accept multiple conductors and electrically bond them together, e.g., a submersible secondary distribution connector, is typically located in a buried space below the transformer terminals. There is no convenient way of physically securing the terminal to the distribution transformer. This may make it difficult to service the new connections due to limited access and visibility of the connections as each connection is now covered with a rubber boot and located near or below ground level and is not physically secured. Having the electrical connections located at or below ground level may create a risk for reliability of the connections due to exposure to water, rodents and other environmental factors. This type of connection may also make it difficult to restore the original connection between the distribution transformer and the one or more loads if the electrical device needs to be taken out of service.
Thus, there is a need for a simple and cost effective transformer coupler secured in close proximity to a distribution transformer to connect at least one electrical device to one or more loads.